Drug-resistant pathogens represent a significant public health problem which can affect individuals at work, at home, and even in the hospital. Methicillin-Resistant Staphylococcus Aureus (MRSA), Vancomycin-Resistant Staphylococcus Aureus (VRSA), Clostridium difficile (C. difficile), and other gram negative pathogens are currently circumventing our traditional approaches to pathogen control, and challenging our capacity to innovate new technical solutions.
In Feb. 10, 2010, Reuters reported that the estimated cost of infections acquired at hospitals alone is $8.1 billion. From a study published in Archives of Internal Medicine that same day, Reuters reported finds by researchers that pneumonia patients stayed an extra 14 days after surgery, and that more than 11 percent of them died. “That's the tragedy of such cases,” said Anup Malani of the University of Chicago, who worked on the study. “In some cases, relatively healthy people check into the hospital for routine surgery. They develop sepsis because of a lapse in infection control, and they can die.” The researchers said that 1.7 million healthcare-associated infections are diagnosed every year. Many are due to drug-resistant bacteria, such as Methicillin Resistant Staphylococcus Aureus or MRSA, which cost more to treat because only a few drugs can work against them. These infections can also be caught outside hospitals, and some studies show that such community-acquired infections are also on the rise. One estimate from Pfizer Inc. suggested that treating MRSA alone costs $4 billion a year.
One of the ways that drug-resistant pathogens can be spread is by cross-contamination, whereby the pathogens contaminate the skin and/or clothing of an individual, and then are transferred from one individual to another through personal contact. The risk of cross-contamination is especially great in public and institutional settings where workers interact with the general public. Examples include hospital emergency departments, hospital infectious disease care units, general hospital environments, long-term healthcare facilities, correctional facilities, transportation screening (such as TSA transport screening), some athletic facilities, law enforcement, corrections, toll booth attendants, theater ticket takers, and EMT and fire services. Many of these facilities have already suffered serious outbreaks of infection, and know from experience that these pathogens can be difficult to control.
One emerging technology which can be used to combat cross-contamination is iodine-based pre-operative skin wash, which offers better pathogen-kill efficacy than chlorhexidine. However, even with these products, MRSA, VRSA and C. difficile remain difficult to control.
Personal protection equipment (“PPE”) such as masks and gloves, gowns, and other protective clothing that can be changed and laundered frequently is often used to protect an individual from exposure to dangerous pathogens, for example in a medical environment, or when investigating a toxic biological spill. Other examples include police, prison guards, custodial personnel, security personnel at airports and other secure installations, toll collectors on roadways, and ticket takers at theaters.
In particular, protective disposable gloves are often worn under such conditions. In these approaches, workers must be trained to be diligent in using the gloves and other protective clothing, and to change them frequently. However, this can lead to considerable cost and waste, as well as loss of valuable time as the user is forced to repeatedly stop whatever he or she is doing so as to sterilize or exchange gloves. In practice, a user may be tempted to minimize compliance with required glove-sterilizing and/or glove-changing procedures, or may occasionally forget to sterilize or change gloves, for example due to being absorbed in performing other duties. Unfortunately, in healthcare settings, management has already learned that procedural controls are not enough. People make too many small procedural errors to rely on this approach exclusively. And in many settings, such as toll and ticket takers, frequent changing of gloves is simply not practical.
In addition, frequent changing of protective gloves can cause contamination of the user, due to handling of used contaminated gloves. If the user fails to properly sterilize his or her hands after removal of contaminated gloves, the user can become infected. Since hand sterilization is typically carried out using an alcohol-based substance, protection from such sterilization does not persist from one glove change to the next, so that even a single failure to properly sterilize hands during a change of gloves can lead to dangerous results.
Of course, exchanging gloves does not provide any protection against cross-contamination that might occur between glove changes. Also, because gloves are typically sterilized by applying an alcohol-based product to the outer surfaces of the gloves, and because these sterilizing products evaporate quickly, this approach to glove sterilization does not provide any protection against cross-contamination between sterilizations.
One approach is to sterilize the user's hands between glove changes with a persistent sterilizing cream, such as a hand cream containing Triclosan, which can provide some back-up protection in case the user's hands are not properly sterilized during a subsequent glove change. However, such a cream may interfere with use of the gloves. Also, abrasion by the glove itself can tend to wear the cream away. In addition, this approach provides no relief from accumulation of perspiration and no added protection against cross-contamination of others if the gloves are not sterilized and/or changed with sufficient frequency.
Efforts to avoid cross-contamination could be much more successful if workers could wear gloves, gowns, and/or other protective garments which were self-decontaminating, and therefore did not need to be changed as often as standard protective garments, and/or could continue to provide protection against cross-contamination even if a busy doctor or nurse, for example, occasionally forgot to change his or her gloves between patients. Many personnel from hospitals, transport security, police, corrections, and other public services typically move from one subject to the next within 30-180 seconds. Therefore, for a self-decontaminating fabric to be effective, it must be able to destroy a wide range of pathogens on its outer surface to a 3-log kill level within 30-180 seconds.
A number of self-decontaminating fabrics are currently on the market, utilizing copper, silver, or hydantoin-attached chloramine. However, for these fabrics the 3-log kill rates for vegetative pathogens are in the range of 1-24 hours, and many, if not most, of these current offerings have little or no affect on endospores such as C. difficile. Therefore, while these fabrics may be useful for other purposes, they are not effective for cross contamination control.
A number of other self-decontaminating fabric technologies have been under development for many years, and some of them have been commercialized, including silver coatings and other metal compounds, phenols, chitosan and PHMB to name a few. However, none of these fabrics can provide a sufficiently fast kill time, all have declining performance after washing and use, and none are rechargeable.
In addition, pathogen-protecting gloves are typically not permeable to water vapor, and can cause accumulation of sweat during long use, leading to discomfort and skin irritation, and possibly leading to unwanted cultivation of pathogens in sweat persisting on the skin of the user.
Under some conditions, PPE equipment must provide physical protection in addition to protection from pathogens. Examples include gloves worn by a medical worker providing hypodermic injections, gloves worn by an environmentalist exploring sharp-edged wreckage at a toxic biological spill, and gloves worn by a law enforcement officer frisking a suspect who may be carrying a contaminated knife or drug-related syringe. It can be difficult for such gloves or other PPE equipment to provide sufficient physical protection and pathogen protection, while at the same time maintaining flexibility and breathability. If a glove is not sufficiently flexible, it will impede the activities of the wearer. And if a glove is not sufficiently breathable, it will cause discomfort and skin irritation if worn for extended periods.
Note that the teachings herein are applicable to a variety of types of PPE equipment, such as masks and even complete protection suits, and that the term “glove” is used generically herein to refer to all such PPE equipment, except where the context specifically requires a hand-worn glove.
What is needed, therefore, is a self-decontaminating protective garment such as a glove that provides persistent protection against both cross-contamination and user contamination, preferably having a 3-log pathogen kill rate of between 30 and 180 seconds, and which is easily recharged for continued, long-term use, while maintaining flexibility and breathability. For some applications, what is further needed is a physical barrier to pathogen penetration, and/or a physical barrier which resists cuts and punctures.